Liver metabolism and energetics of 24 patients with liver disease were studied using phosphorus-31 magnetic resonance spectroscopy. Significant abnormalities were detected in the majority of these patients. A striking diversity in metabolic patterns was observed. Patients with acute viral hepatitis had low liver phosphodiesters and high phosphomonoesters, possibly phosphocholine and phosphoethanolamine. In alcoholic hepatitis phosphomonoesters were raised. Intracellular inorganic phosphate and inorganic phosphate/ATP ratios were decreased in primary biliary cirrhosis and in some patients with hepatitis. These spectroscopic results were evaluated in respect of the pattern of liver damage and cellular regeneration. Liver tumours had raised phosphomonoesters and also showed evidence for altered spin-lattice relaxation of the phosphorus nucleus in various metabolites. In iron overload the liver ATP resonances were broadened. The line broadening correlated with the degree of iron overload suggesting the potential use of P-31 magnetic resonance spectroscopy for measuring liver iron